Many pressure set tools are offered that can be set with building tubing pressure against an obstruction such as a seated ball in the tubular string with a port to communicate to a setting piston to move tool components to the set position. In some cases the operator requires an ability to use the annulus hydrostatic pressure in conjunction with added annulus pressure to also set the tool. Either of these methods could be primary. In the instance where added pressure to the annulus is to be the trigger for setting the tool one way the setting has been accomplished is to isolate an external setting piston from well fluids on the way into the well. When the tool is properly positioned, pressure is built above the hydrostatic pressure at the setting depth. More recently setting depths have increased to 10,000 meters making the hydrostatic pressure alone very high. Raising the annulus pressure from the surface further increases the pressure at the setting tool so that a frangible member breaks to allow annulus pressure to one side of an operating piston. The other side of the piston is referenced to a sealed chamber with essentially atmospheric pressure. Pressure differential moves the piston to set the tool such as a packer by diminishing the volume of the atmospheric chamber. While the pressure in the atmospheric chamber rises somewhat from the volume reduction, the end pressure is still infinitesimal when compared to the hydrostatic pressure that continues to act on the other side of the piston even after the applied pressure that broke the frangible member is withdrawn. However, the subterranean tool and its setting module that includes the setting piston will need to stay downhole for the service life of the tool design. The piston continues to see a very large net force over the service life of the tool design. This ongoing large net force has to be accounted for in the component designs of the setting tool and the subterranean tool. The fact that such a high residual force remains causes compromises to be made in other design parameters that may be less than optimal. For example materials need to be selected that have a higher strength that may add cost over less expensive or weaker metals. The flow bore may need to be reduced to allow use of thicker parts to resist collapse force. Ideally if such design compromises could be avoided with a simple modification to the known designs then greater design independence can be accomplished that results in greater tool performance and optimized cost. In essence the present invention addresses this problem with a solution that communicates the atmospheric chamber to the surrounding annulus pressure to eliminate the large residual net force on the setting piston after the setting piston has stroked and set the tool. A preferred way this is done is to use two pressure levels with a first acting to set the tool by moving the piston and a second and higher level acting to communicate the atmospheric chamber with the surrounding wellbore annulus hydrostatic pressure. Other alternatives to accomplishing the reduction of pressure differential on the actuating piston after it strokes to set the tool are also envisioned. Those skilled in the art will understand further aspects of the invention from the description of the preferred embodiment below with the associated drawings while understanding that the full scope of the invention is to be determined from the appended claims.